“Cup chuck turning” is the expression used for the turning of wood articles such as goblets, spinning tops etc from a piece of wood. This activity usually involves forcing a taper-turned piece of wood into a cone shaped hole in a cup chuck or screwed into a cup chuck that has a special internal thread.
However, these types of cup chucks cannot be used to perform angular offset turning. There is however one cup chuck that has been developed with angular offset capability. This chuck was developed by Jean-Francois Escoulen and is described in the book, “Woodturning in France” (Editions Vial, Spain, May 1998, ISBN: 2-85101-063-8). This particular cup chuck comprises a cylindrical body for attachment to the headstock spindle of a lathe and a spherical ball that rotatably engages with a hollowed out section in the cylindrical body. The spherical ball can then be adjusted into a number of orientations with respect to the cylindrical body to achieve an angular offset. It achieves this by way of set screws that passes through a hole in the cylindrical body and can be screwed up against the spherical ball. The spherical ball includes an attachment means to secure a workpiece to itself and thus it can be used for angular offset woodturning.
This chuck however, does not afford discrete angular offset adjustments to the workpiece. This means that it is very difficult to return to a particular angular offset used previously. This deficiency means that it is difficult to replicate a previous work or to craft a work using one particular offset angle in multiple instances. Another deficiency results from the imprints the set screw produces on the spherical ball whilst tightening the screw there-against. These imprints roughen the surface of the spherical ball and make precision adjustments of the spherical ball with respect to the cylindrical body difficult.
The present invention seeks to provide a chuck for angular offset woodturning that will overcome or substantially ameliorate some of the deficiencies of the prior art.